SOLUTION: If the radius of a sphere is increasing at the rate of 2 inches per second, how fast, in cubic inches per second, is the volume increasing when the radius is 10 inches? (A) 40&#

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Question 263130: If the radius of a sphere is increasing at the rate of 2 inches per second, how fast, in cubic inches per second, is the volume increasing when the radius is 10 inches?
(A) 40π
(B) 80π
(C) 800
(D) 800π
(E) 3200π

Answer by drk(1908) About Me  (Show Source):
You can put this solution on YOUR website!
We start with the volume of a sphere formula as
V+=+%284%2F3%29%2Api%2Ar%5E3
take a derivative to get
dV%2FdT+=+4%2Api%2Ar%5E2%2A%28dR%2FdT%29
we are told that dR/dT = 2, and r = 10, so we get
dV%2FdT+=+4%2Api%2A10%5E2%2A%282%29
which is
dV%2FdT+=+800%2Api
or choice D